Known techniques for evaluating rice and other grains include evaluation by appearance quality grade. This evaluation is performed on the basis of the well-ordered kernel percentage, which is the weight ratio of well-ordered kernels among the grains, or the weight ratio by appearance quality grade of the grains.
In order to calculate each of the above-mentioned weight ratios, it is necessary to sort, grain by grain, the grains that have been hulled into well-ordered kernels and waste kernels, or into well-ordered kernels and cracked-germ kernels, immature kernels, dead kernels, colored kernels, damaged kernels other than cracked-germ kernels, and the like; and to weigh the sorted grains. The calculation is therefore cumbersome and time-consuming.
Therefore, there is a known technique in which a grain appearance quality grade discrimination device is used to calculate the weight ratio by quality grade of grains.
The grain appearance quality grade discrimination device is a device in which, e.g., a scanner is used to simultaneously image about 1000 sample grains, and image information obtained by the imaging is used to discriminate the quality grade of individual sample grains; and in which it is possible to readily evaluate the quality grade of edible grains (see Patent Citation 1, 2).
FIG. 6 shows a conventional workflow for using a grain appearance quality grade discrimination device according to Patent Citation 1 to calculate the weight ratio by quality grade of grains.
(1) Imaging Processing (S11)
The grain appearance quality grade discrimination device images sample grains of the grains to be evaluated and acquires imaging data for the sample grains.
(2) Data Processing (S12)
The grain appearance quality grade discrimination device extracts data relating to the quality grade of the sample grains on the basis of the imaging data.
(3) Quality Grade Discrimination Processing (S13)
The grain appearance quality grade discrimination device compares the data relating to the quality grade of the sample grains to a threshold value that has been predetermined, and thereby discriminates the quality grade of the sample grains.
(4) Grain Number Tallying Processing (S14)
The grain appearance quality grade discrimination device tallies grain numbers by quality grade with regards to the sample grains whose quality grade has been discriminated.
(5) Weight Ratio Calculation Processing (S15)
The grain appearance quality grade discrimination device calculates the weight ratio by quality grade on the basis of grain numbers of the sample grains tallied by quality grade and a weight conversion coefficient per grain (single-grain weight) that has been set for each quality grade in advance.
(6) Output Processing (S16)
The grain appearance quality grade discrimination device outputs, to a printer or a monitor, a calculated value of the weight ratio by quality grade of the sample grains.
FIG. 7 shows an example of calculating the weight ratio by quality grade of unpolished rice grains according to the above-mentioned conventional method. In FIG. 7, the quality grade of the unpolished rice grains is represented as “discrimination classification”.
As described further above, in the grain appearance quality grade discrimination device, a weight conversion coefficient per grain (single-grain weight) of unpolished rice is predetermined for each of the discrimination classifications (quality grades).
The grain appearance quality grade discrimination device then multiplies a grain number of sample grains tallied by discrimination classification (quality grade) by the weight conversion coefficient (single-grain weight), and thereby obtains a converted weight. Then, a proportion of the converted weight in relation to a total weight is calculated as the weight ratio by discrimination classification (quality grade).
According to a method in which the above-mentioned grain appearance quality grade discrimination device is used, it is possible to calculate the weight ratio by quality grade of grains in a simple and speedy manner.
When grains are observed in detail, individual sizes differ amongst grains that are classified into the same quality grade.
FIG. 8 shows an example of comparing two broken grains.
The broken grain shown in FIG. 8(a) and the broken grain shown in FIG. 8(b) clearly differ in size.
However, the method in which the above-mentioned conventional grain appearance quality grade discrimination device is used is one in which both grains are treated as a single broken grain and the converted weight is obtained by performing a multiplication using the same weight conversion coefficient (single-grain weight); it is not necessarily possible to calculate the weight ratio in an accurate manner.